70 ON THE MOTION OP THE BLOOD. 



them from the arteries, it cannot but happen that this 

 blood, driving against the right auricle, must excite it 

 to resistance for some time after the death of the left 

 portion of the heart. 



118. This congestion on the right side of the heart 

 affords an explanation of the small quantity of blood 

 found in the large branches of the aorta. Weiss,* and 

 after him Sabatier,f ascribe to this cause likewise the 

 comparatively larger size % of the right auricle and 

 ventricle in the adult dead subject especially. 



119. The motion of the blood is performed by these 

 two orders of vessels in conjunction with the heart. Its 

 celerity in health cannot be determined : for it varies 

 not only in different persons, but in different parts of 

 the same person. Generally, the blood moves more 

 slowly in the veins than in the arteries, and in the small 

 vessels than in the large trunks. But these differences 

 have been overrated by physiologists. 



The mean velocity of the blood flowing into the 

 aorta, is usually estimated at eight inches for each pul- 

 sation, or at fifty feet in a minute. 



120. Some have affirmed that the globules of- the 

 cruor move more in the axis of the vessels, and with 

 greater rapidity, than the other constituents of the 

 blood. I know not whether this rests upon any 

 satisfactory experiment, or upon an improper appli- 

 cation of the laws of hydraulics; improper, because 



• J. N. Weiss, De Dextro Cordis FetUriruli, pott mortem ampliori. AJtorf. 

 1767. It... 



t Ant. Cliauin. Sabatier, lit vitis tmimsthbiit; Vcntriculorum Cordis cadem 

 tapacitas. Paris. 1772. 4to. 



J Sani. AurmHns, Dt Vmonsm PulmoHal. fy Cavitat. Cordis inteqm,U 

 amplitudine. Gutting. 1750. 4to. 



